Clark was one of several attending physicians at Parkland Memorial Hospital in Dallas on Nov. 22, 1963, when the president entered the emergency room. He pronounced Kennedy dead at 1 p.m. by referring to the watch, according to his family, and signed the death certificate.

"There is endless debate among historians on the actual time of death and there was most likely also a clock in the ER," said John Reardon, Christie's international co-head of watches. "However, the family and historians agree to these facts: the watch was on his wrist that day and he called the time of death and signed the death certificate."

Friday marks the 50th anniversary of Kennedy's assassination.

The Reference 1463 Patek was the Geneva-based company's first water-resistant chronograph wristwatch. It is being sold by Clark's direct descendants) and comes with its original red clamshell box, sales receipt and Patek Philippe certificate. The back is engraved with the doctor's name.

Clark, who died in 2007, created the neurosurgery service at Southwestern Medical School and Parkland Memorial Hospital in 1956 and the neurosurgery residency program in 1962.

A portion of the proceeds from the auction will be donated to the Red Cross.